The mission the UNTHSC Research Office is to assist all components of the Health Science Center in identifying research opportunities, securing support, overseeing research and insuring research, funding policies and compliance.

Research

Dr. Muchlinski’s research focuses on primate bioenergetics and sensory ecology within an anthropological framework. Specifically, this work concentrates on how the selective pressures imposed by differences in feeding ecology shape the anatomy, physiology, and evolution of both non-human primates and humans.

She is currently involved in two ongoing research projects:

The first focuses on the interaction between brain size and the evolution of metabolic strategies. Primates have larger brains than most non-primate mammals, yet we do not have significantly different overall metabolic requirements for our body size. The allocation of caloric resources throughout an organism depends on 1) body composition and 2) variation in the metabolic rate of particular tissues resulting from changes in vasculature, mitochondrial density, and gene activity. The Energy Trade-Off Hypothesis predicts that large-brained animals can maintain a balanced energy budget by offsetting the increased metabolic cost associated with a large brain, with reductions in the size of other costly tissues (for example, gastrointestinal tract). Her work shows that all primates, (including humans), are under-muscled compared to most non-primate mammals. To better understand this phenomenon, her current research asks the following three questions: 1) Does relative muscle mass vary with brain size in primates? 2) Does muscle fiber composition correlate with relative brain size in primates? And 3) Is there a peak in muscle growth soon after brain growth is complete? Her findings show that there is, in fact, a negative correlation between brain size and muscle mass in primates and the mammals sampled. These results are further supported by a negative correlation between Type-I muscle fibers and brain size. Type-I muscle fibers are different from other muscle fibers (for example Type-II and IIx), because Type-I fibers use more oxygen and are able to produce the most adenosine triphosphate (energy) from glucose. The brain also requires a significant amount of glucose. Thus, animals with larger brains (and therefore higher glucose demands) are expected to have less muscle and a lower percent of Type-I muscle fibers than animals with smaller brains. Overall, primates have fewer Type-I fibers than non-primate mammals. Ultimately, this research has implications for both human evolution and human health (for instance, Type-II diabetes research).

The second project is a collaborative effort focusing on midfacial growth trajectories in sub-adult primates. With her colleagues, she is exploring the anatomical and developmental basis of the documented sensory trade-off between olfaction and the visual system. This study applies traditional (histology) and modern (Computed Tomography Imaging) approaches to the analysis of facial growth/reduction in primates, with a focus on the connections between anatomy (nasal and orbital regions) and evolutionary factors such as stereoscopic vision, diet, and life history. Preliminary results indicate that a relatively long gestation period in primates is not only tied to an extended period of brain development, but also to an extended period of visual system development because the eye is essentially an outgrowth of the brain.

Muchlinski MN and Deane AS. 2014. How strong is the frugivory signal? The interpretive power of infraorbital foramen area in making dietary inferences in extant apes. Anatomical Record. DOI: 10.1002/ar.22953

Muchlinski MN. 2010. A comparative analysis of vibrissa count and infraorbital foramen area in primates and other mammals. Journal of Human Evolution 58: 447-473

Muchlinski MN.2008. The infraorbital foramen, infraorbital nerve, and maxillary mechanoreception: Implications of interpreting the paleoecology of fossil mammals based on infraorbital foramen size. The Anatomical Record 291:1221–1226